The present invention pertains to a shifting device of a transmission, especially an automatic transmission, of a motor vehicle, which can be in at least one secured state and one unsecured state.
Such a secured state of the shifting device, more precisely of the selector lever, is used, e.g., in order to embody a so-called xe2x80x9cKey Lockxe2x80x9d or xe2x80x9cShift Lockxe2x80x9d system on a shifting device, where it is ensured hereby that the selector lever can be moved from a certain position, e.g., from the xe2x80x9cPxe2x80x9d position, only when either the ignition key of the vehicle is in a certain position and/or the brake of the vehicle is actuated. It is ensured here by a corresponding mechanism or another device that unlocking of the selector lever is possible only when the vehicle is in a certain configuration, e.g., with the brake actuated, whereas unlocking of the selector lever and consequently putting the vehicle into gear is prevented in other configurations of the vehicle.
A similar shifting device has been known, e.g., from the patent specification U.S. Pat. No. 5,402,870. This is a shifting device for an automatic transmission, which can be in a secured state and in an unsecured state, where a pivotable selector lever is present for selecting different gear selections and the selector lever has a first locking mechanism, which can block the pivoting movement of the selector lever, and this first blocking mechanism has a displaceable blocking element (detent pawl), which can engage a stationary blocking contour on a blocking plate (detent plate) and prevents the selector lever from being pivoted in case of the blocking element engaging the blocking contour. Furthermore, the shifting device has a second blocking mechanism with a toggle lever, which is in contact with a stop in a stretched-out blocking position and indirectly prevents the first blocking mechanism from being released by means of a bolt by engaging a push rod which is displaceable axially to the selector lever and to which the blocking element is fastened, while the toggle lever makes possible the unlocking of the first blocking mechanism in the bent position by the bolt, which has blocked the axially movable rod, being retracted.
In the blocking position of the toggle lever, i.e., in a stretched-out position, in which the toggle lever is bent only slightly, the center of the toggle lever is in contact with a stop in the area of the pivotable connection between the two legs of the toggle lever, so that the toggle lever securely maintains its stretched-out position. If the toggle lever is to be transferred from this stretched-out blocking position into a bent release position, an electromagnetically controlled releasing device acts on the center of the toggle lever and pulls the toggle lever into a bent position, in which the blocking of the displaceable rod is abolished.
The drawback of this prior-art device is that a relatively large number of movable parts are needed to embody this. As a result of the manufacturing costs are high, on the one hand, and there is a high probability that frequent repairs will be needed, on the other hand.
The object of the present invention is to find a shifting device which can be in at least one secured state and an unsecured state, wherein the number of movable parts shall be as low as possible.
The inventor has recognized that a substantial simplification of the shifting device can be achieved by an improved arrangement and more favorable working point of the toggle lever.
Thus, according to the invention an automatic transmission of a motor vehicle, which can be in at least one secured state and one unsecured state has a pivotable selector lever for selecting different gears and/or gear selections and has a first blocking mechanism, which can block the pivoting movement of the selector lever. The first blocking mechanism has a displaceable blocking element and a stationary blocking contour for engaging the blocking element and can prevent the selector lever from being pivoted by the blocking element engaging the blocking contour. A second blocking mechanism has a toggle lever, which is in contact with a stop in a stretched-out blocking position and prevents the release of the first blocking mechanism and makes possible the unlocking of the first blocking mechanism in the release position. A release mechanism releases the toggle lever from the stretched-out blocking position. The toggle lever is arranged such that one leg of the toggle lever acts on the blocking element of the first blocking mechanism.
It is achieved due to this arrangement of the at least one toggle lever according to the present invention that the blocking element is not acted on any more by the manually actuated means, which can bring about the disengagement of the blocking element from the blocking contour, but directly by the toggle lever itself, without a mechanical roundabout way, and it blocks this blocking element as the case may be, so that pivoting of the selector lever is not possible. Due to this change in the working point of the toggle lever, it is possible, e.g., to do away with a bolt at the toggle lever, as it is present in the state of the art and which can block the movement of a rod. Furthermore, it is also possible to block first blocking mechanisms of various designs as a result.
Provisions are made in a special embodiment of the shifting device according to the present invention for the leg of the at least one toggle lever acting on the blocking element to be connected to the blocking element in a rotatingly movable manner, where the blocking element may preferably form an axis of rotation of the leg at the same time. Such an embodiment is embodied, e.g., in the following exemplary embodiment. However, it is also obvious that the blockage of the blocking element can be brought about by a leg extending only under the corresponding blocking element and thereby bringing about a blockage, without having to be rigidly connected to this blocking element. The exemplary embodiment to be described later shows a shifting device, in which the blocking element is arranged at a push rod displaceable axially in relation to the selector lever, where the push rod also extends in the selector lever itself here.
However, an embodiment is also possible, in which the blocking element is arranged at the end of a bowden cable that can be actuated manually, so that the displaceable rod can be replaced with a bowden cable, which can now be arranged in any desired manner.
According to the present invention, the stationary blocking contour may also be, e.g., part of a blocking plate connected to a shifting device housing. However, it is also possible, for instance, to accommodate the blocking contour in other stationary elements of the shifting device, e.g., at the housing, so that the blocking element engages a contour of the shifting device housing.
In another special embodiment of the shifting device, the inventor proposes that the release mechanism for releasing the toggle lever from the stretched-out blocking position have an electromagnetically or hydraulically movable pushing element, preferably a bolt, which can bring about the bending of the toggle lever. If an electromagnetically movable pushing element is embodied, the particular position of the toggle lever can be brought about in the sense of a xe2x80x9cKey Lockxe2x80x9d or xe2x80x9cShift Lockxe2x80x9d, e.g., by means of an electric switch, which is connected to the brake pedal, and/or a switch that is connected to the ignition lock.
However, it may also be particularly advantageous for the releasing device to have a hydraulically movable pushing element. As a result, a hydraulic connection can be established between the brake circuit system and the pushing element, so that release of the toggle lever can indeed take place only when a corresponding hydraulic pressure builds up in the brake system of the vehicle. This means that the release of the secured state is made possible only when the brake system indeed functions and not already when the brake pedal is simply actuated. An additional safety aspect is achieved as a result, because the vehicle is secured from starting moving even in case of failure of the hydraulic system of the brake system.
According to another embodiment of the shifting device, the inventor also proposes that the release mechanism for releasing the toggle lever from the stretched-out blocking position have an electromagnet, wherein a permanent magnet, which is located directly opposite the electromagnet in the stretched-out blocking position and wherein the electromagnet generates a magnetic field repelling the permanent magnet to release the toggle lever, is arranged in the center of the toggle lever.
In another embodiment of the shifting device, it is proposed that a securing element, which holds the toggle lever reversibly in the stretched-out position, wherein release of the toggle lever cannot be brought about accidentally even by the vibration of the vehicle, be provided at the toggle lever.
Such a securing element may be, e.g., a spring element, which acts on the legs of the toggle lever and holds the legs of the toggle lever in the stretched-out blocking position by a gentle pressure, as is shown in the exemplary embodiment to be described below.
In another embodiment of the securing element, a permanent magnet may be provided, which is arranged at and acts on the axis between the legs of the toggle lever and holds the toggle lever as a result in the stretched-out blocking position with a weak magnetic force. If this variant of the securing element is embodied in conjunction with the release mechanism by an electromagnet, the permanent magnet may be, e.g., the core of the electromagnet, whose pole is reversed in case of release by a correspondingly stronger electromagnet and leads to a repelling effect at the toggle lever and brings about the release of the toggle lever as a result.
Provisions are made in another preferred embodiment of the shifting device for arranging two toggle levers on both sides of the selector lever, where at least one opposite toggle lever leg pair each and preferably both toggle lever leg pairs may be connected to one another such that a synchronous movement of the toggle levers arranged on both sides is forced to take place.
It is pointed out that the shifting device according to the present invention may be a shifting device that transmits its shift commands to a manual transmission or automatic transmission either mechanically or in a powerless manner, e.g., electrically or optically.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.